High precision gantry machine with expansion joint

A Cartesian gantry system for mounting on a rigid base comprising:

• a) spaced and parallel linear Y-translation stages comprising linear bearings with associated linear motors, the linear bearings defining the Y-direction and constraining the motion of Y-carriages riding on the linear bearings,
• b) a bridge for supporting a linear X-translation stage comprising a linear bearing with an associated linear motor, the linear bearing defining the X-direction, being perpendicular to the linear bearings associated with Y-translation stages and constraining the motion of an X-carriage riding on the linear bearing, said bridge secured at each end to a Y-translation carriage by a bridge extension plate extending over a Y-carriage,
• c) an expansion joint between the bridge and a Y-carriage at only one end of the bridge comprising:
• i) a bridge extension plate integral with the bridge having a lower surface parallel to the X- and Y-directions and extending over the Y-carriage and support flanges connected to and extending perpendicular to the bridge extension plates at each end of the bridge having parallel edge surfaces parallel to the X-direction,
• ii) a flexure plate having upper and lower surfaces parallel to the X- and Y-directions, at least portions of the upper and lower surfaces of said flexure plate abutting the bridge extension plate and the Y-carriage, said flexure plate having sections aligned in the X-direction, a central section, two outer sections spaced from the central section in the Y-direction, and two flexure sections joining the central and outer sections, respectively, enabling small relative X-direction movement of the central and outer sections by elastic deformation of the flexure sections,
• iii) fasteners securing the central section of the flexure plate to one of the bridge plate or the Y-carriage and fasteners securing the outer sections of the flexure plate to the other of the bridge plate or the Y-carriage, and
• iv) bolster flanges connected to and extending from the Y-carriages at each end of the bridge having edge surfaces parallel to the X-direction and parallel and adjacent to the edge surfaces of the support flanges associated with the bridge.